This is a browser agnostic question but we're testing with IE9.
One of the web apps our users visit is being randomly cached and changes aren't showing up when they should. No other site has this issue and we've worked with the vendor who claims it isn't happening to anyone else. If we use the developer toolbar and select "force refresh from server" everything updates correctly.
Instead of truly solving the issue our thought is to work around it by disabling cache for this specific site. However, we don't know how.